Spark-plug.



E. MGFARLAND L E. C. CHURNING.

SPARK PLUG.

APPLlGATION FILED MAYB, 1913 Patented July 14, 1914.

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UNITED STATES rA- FETE.

SPARK-PLUG.

Specification of Iietters Patent.

Patenten aan it., rara..

Application led Kay Si, 1913. Serial No. 766,377.

To all whom it may concern Be it known that we, EARL MCFARLAND a-nd EDWARD C. CHURNING, citizens of the,

the art to which it appertains to make and use the same.

This invention relates to new and use-ful improvements in duplex or multiple spark plugs yfor internal combustion engines.

As its principal obj ect this invention aims to provide a device of this character in which the spark gap may be varied by means operable exteriorly of the engine cylinders. l

A further object resides in the provision of a multiple spark plug in which the igni* tion of the gases may be accomplished by either a battery or a magneto current, or both.

A still further object is to provide a spark plug so constructed that the sparking point of the magneto circuit and the batter circuit Inay be independently adjusted exteriorly of the engine, and without necessitating the removal of the plug.

. The above and additional objects are accomplished by such means as vare illustrated in the accompanying drawings, described in the following s ecification, and then more particularly p01 ted out in the claims which are appended hereto and for-m a part of this application. p

With reference to the drawings, wherein we have illustrated the preferred embodi ment of our invention 'as it is reduced to practice, and throughout the several views of which similar reference numerals designate -corresponding parts: Figure 1 isa vertical secbion of the preferred form of this invention. 2V is a top plan view of the preferred form. view of the preferred form. Fig. 4 is a vertical section of the modified form. F ig. 5 isa bottom plan view of the modified form.

Proceeding now to the description of the drawings, the preferred embodiment of this invention, as illustrated in Figs. l, 2 and 3,

includes a plug body l, consisting of the t as indicated at 5. v

formed `ot any standard materialsuch as Fig. 3 is a bottom plan customary threaded bushing made of steel,l

brass, or bronze, reduced at its 'lower portion, and externally sc rew threaded, as at 2, in the usual manner for permitting the bushing to be threaded into a hole tapped in the engine cylinder. rEhe bushing l is cored in the usual mannerto provide a pair of electrode receiving passages, which, in this invention, are downwardly convergent. The upper portion of each of the electrode passages is enlarged and outwardly oset as regards its angularvrelation to the longitudinal axis otr the bushing. llnasmuch as each electrode and the insulation therefor is similar in construction and arrangement, it is deemed necessary to describe only one ot the elements. At the juncture of the enlarged portion 3 with the lower reduced portion t ot the electrode bore, the passage is enlarged -to provide an annular recess, An insulating tube 6,

porcelain, mica, or steatite, is arranged in the reduced portion 4 of the bore, and carries at its upper terminal an annular laterally extending flange 7 which is disposed to rest on the bottom face of the annular recess 5, as will be observed by reference to Fig. 1. Extending upwardly through the enlarged portion 3 is an insulating tube 8, carrying at its lower terminal a lateral annular flange 9 which, in the preferred embodiment, is molded integrally with the member 7. There is thus provided an annular chamber at the junction of' the members 7 and 9, wherein is arranged a collar.

10 formed at the junction of the upper and lower sections 11 and 12, respectively, ott' the electrode. After the electrode and its insulating tube have been arranged inthe receiving passage, a bushing 1.3,. provided with the usual nut head and externally screw threaded reduced portion, is slipped over the electrode, and is threaded into the enlarged portion 3 of the passage. llt will be readily observed that by threading the member 13 into severe engagement with the member 9, that the insulating tube and the ,electrode are held in secure fixed position. rl`he upper portion of the electrode is threaded in the usual manner and carries. the customary binding nuts 14 and l5, the member 15 being insulated :from the bushing by an insulating washer 16.

Centrally of the. bottom v:tace of the...re.

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duced portion 2 of the plug body is mounted a platinum ground point 17 which may be threaded into the member 2 to facilitate .the removal of a worn point, and the substitution of a new ground point. The lower projecting terminals of the electrodes carry platinum-points, as indicated at 18. These members 18 are bent inwardly in the direction of the member 1747 and may be adjusted to produce the desired spark gap previously to the application of the plug tothe cylinder.

From the foregoing it will be observed that the preferred form of this invention provides a sparkplug in which a battery circuit and a magneto circuit may be simultaneously or selectively employed. In this connection it is to be noted that the positive battery wire maybe -attached to one elec trede and the positive magneto wire to the other electrode, the negative of each circuit being grounded in the usual manner.

In the modified form of this invention,- illustrated in detail in Figs. 4 and 5, there has been provided a spark plug in which the length of the spark gap may be eXteriorly adjusted to provide a means for quickly remedying inefficient sparking, frequently resulting from worn points or improper primary adjustment of the spark gap. To this end, the iianges' 7 and 9 of the preferred form which are designated by the numerals 20 and 21, respectively, in the modified'form, and are molded separately, as will be noted by reference to Fig. 4, thus producing two separate insulating tubes 22 and 23.' Reference now being had to Fig. 5, it will be observed that the platinum points 24 and 25 of the electrodes are of greater length than the points in the preferredwform, and that the electrodes 26 and 27 are arranged at a greater distance from the ground points 28. The construction of `the remaining features of the modified embodiment are similar to the corresponding features of the preferred embodiment.

It will be apparent that by merely forming the insulation into separate tubes 22 and 23,A that thebushings 29 of the modified form may be partially withdrawn from their receiving bores, to permit the electrodes 26 and 27 to b e rotated. As indicated by dotted lines in Fig. 5, the rotation of the electrodes will act to increase or di- -minish the length of the spark gap. After the electrodes have been manipulated, to produce the desired spark gap, the bushing 29 is again threaded into severe engagement with the member 21 of the tube 23, thus clamping the. collar 30 of the electrode and holding the electrodes in adjusted position. The manipulation of the bushing 29 and the electrodes, during the adjustment of the spark gap.l Will be apparent upon reference to Fig. 4, in which the electrode on the left hand is shown in position for adjustment, while the electrode on the right is Shown in clamped adjusted position.

It is desirable to emphasize the fact that the provision of the multiple circuit plug in which the spark gaps are exteriorly a`djustable, ,is regarded as a feature of utmost importance. The importance of the feature above noted will be apparent when it is considered that inasmuch as the E. M. F. of a magneto circuit is eater than the E. M. F. of a battery circuit, (unless the current of the latter circuit be passed through a spark coil of unusual strength,) it is necessary to provide a smaller spark gap for the battery circuit.

In reduction to practice, we have found that the form of our invention, illustrated in the drawings and referred to in the above description, 'as the preferred embodiment, is the most eiiicient and practical; yet, realizing that the conditions concurrent with the' adoption of this device will necessarily vary, we desire to emphasize the fact that various minor changes in details of construction, proportion and arrangement `of parts may be resorted to, when required,

without sacrificing any of the advantages of our invention, as defined in the appended claims.

What is claimed is:

1. A spark plug including a cored body member, a ground point threaded in said body member, said body member being provided with a pair of downwardly convergent electrode bores, each of said bores being enlarged and internally screw threaded at its upper terminal, an annular recess formed at the junction of the enlarged portion of the bore and the lower reduced portion, an insulating tube for said lower portions of each bore, an annular fiange formed on said tube and arranged in said annular recess, an insulating tube for said upper enlarged portion of each of said bores` an annular ange carried by said second tube and arranged in said annular recess, a pair of electrodes ar ranged in said bores, a collar carried by each of said electrodes and mounted between the said tube flanges, and a clamping bushing for each of said electrodes, said bushing being threaded in said enlarged upper terminal of said passages.

2. A spark plug including a body member, a pair of electrodes arranged in said body member, insulating tubes for each of said electrodes, laterally extending platinum points'for each of said electrodes, a ground point threaded in said body portion and arranged between the said electrodes, said elec'- trodes being adapted to rotation for varying the distance of the points from the ground point, and means for clamping the electrodes in adjusted position.

3. A spark plug comprising a body portion having a pair of'downwardly converging electrode bores formed therein, a pair of'elect'rodes mounted within said bores, insulating tubes'for eac-h of said electrodes mounted within the bores, lateral points for each of said electrodes disposed in spaced relation to each other, a ground -point removably secured to said body portion between the electrode points, means for preventing longitudinal movement of said electrodes relative to the body portion and permitting rotary movement and means for clamping thel electrodes in adjusted position.

4. A spark plug comprising a body porf tion having a pair of downwardly converging electrode bores formed therein, an electrode mounted withln each of sald bores, an

insulating tube for each of said electrodes,

a laterally extending point formed integral with each ofsaid lectrodes, a ground point secured to said body portion adjacent the electrode points, means for preventing 1ongitudinal movement of the electrode relatively to the body portion and -for permitting rotary adjustment of the electrodes and means for clamping the electrodes in adjusted position.

In testimony whereof we aflX our signatures in presence of two witnesses.

^ EARL MCFARLAND. y ED'WARD C. CIIU|Rl\TIl\TGr.l Witnesses C. C. BoNHAM,

REID ARNOLD. 

